SpatialLITE is a modern, lightweight .NET library for spatial data processing. The goal of the library is to make spatial data processing faster, easier and more intuitive. It is FREE (distributed under the New BSD license).

SpatialLITE supports many data formats, basic topology analysis of geometry objects and their measurement.
Object model of the library is inspired by OGC Simple Feature specification, but it was enhanced to take advantage of the .NET enviroment (e.g. generics).

SpatialLITE library is being developed in C# on top of the .NET 4 framework. Right now it is in the beta stage and any feedback is highly apprised. You can download lateset stable version in the download section.